Abstract

The mind-body problem is the problem: what is the relationship between mind and body? In this project, I claim that the relationship between the experience of pain and specific physiological mechanisms is best understood as one of type identity. Specifically, the personal experience of pain is an allostatic stress mechanism comprised of interdependent nervous, endocrine and immune operations.In Chapter One, I provide five reasons to prefer type identity theory of mind to dualistic philosophies of mind: it has greater explanatory power; it is more respectful of philosophical and folk intuitions about the causal powers of qualia; it is simpler; it is supported by the causal closure of the physical; and it is continuous with the natural sciences and not separate from them. I describe and challenge four philosophical objections to type identity theory of mind: mental states are excluded; mental states disappear; inverted qualia; and Saul Kripke‟s claim that type identity theory is false because two individuals could have the same mental state while having different physiological states.In Chapter Two, I advance a type identity theory of pain supported by a robust theoretical schema as the best description of the mind-body puzzle: what is pain? I frame a well established multilevel descriptive view of the physiological mechanisms that describe pain qualia within the context of advancing theoretical descriptions of the nervous, endocrine and immune systems and their functional interdependencies, and descriptions of allostasis, homeostasis, stress and wounds, all constrained in turn by complex adaptive systems theory. A biological individual is a complex adaptive system coping with a physical and social environment, but possessing nested subsystems. Taken together, these descriptions show how pain qualia are type identified with specific neurophysiological mechanisms; namely: (1) somatosensory qualia of pain, including submodality, intensity, duration and location, are best described as the operations of multisubsystem mechanisms in the neospinothalamic tract; (2) negative emotional pain qualia are the operations of multisubsystem mechanisms in the paleospinothalamic tract; (3) cognitive pain qualia (pain anticipation) are the operations of primary somatosensory cortex (neospinothalamic tract); (4) pain suppression (stress-induced analgesia) are the operations the dorsolateral funiculus pathway and opiate systems (paleospinothalamic tract). The simplest and most parsimonious metaphysical description of these robust relationships is that pain is mechanism.In Chapter Three, I advance a novel polyvagal-type identity theory of pain facial expression to best explain the explanatory mind-body puzzle: how can pain exist? According to some philosophers, assuming neuroscience explains with what mechanistic operations being aware of a burning arm pain is type identical, it is still impossible for any neuroscientific theory to explain how a specific pain must be correlated with a specific mechanism, as opposed to a different mechanism. Thus, there appears to be an explanatory gap. In this chapter, I will attempt to bridge the explanatory gap in two ways. First, based on the theoretical approach for a type identity theory of pain offered in Chapter Two, I offer a polyvagal-type identity theory of the mammalian pain face. I claim type identity theory of mind best explains how the gap can be bridged. Type identity theory of mind makes a realist assumption that pain is causally responsible for behaviours such as facial pain grimaces and screaming. Second, I attempt to bridge the gap by arguing that the supposed gap assumes that type identity theory must reconstruct type pain identities as formal derivations from laws of nature. Based on actual scientific practice and philosophical considerations concerning explanatory levels, I will show that this is a false assumption. Type identity statements that successfully emerge from mechanistic pain explanation are between different delineations of pain phenomena at the same explanatory level; they are intralevel. Although the explanatory gap puzzle correctly shows our incomplete understanding of how pain might be explained by mechanism, the gap merely asserts a practical limit on our present explanatory successes, and is not in principle unbridgeable on a priori grounds, as some philosophers claim.Eliminative materialists also assert that there is nothing more to pain than mechanism, but deny that pain can be type identified with neurophysiological mechanism. The reason is that pain does not really exist. Eliminativists propose that pain is part of folk psychology which consists of false generalizations („wounding is the cause of pain‟) and false theoretical claims ("pain always hurts‟). Thus, pain should be eliminated and replaced by an accurate neuroscientific successor theory. In Chapter Four, I assess philosophical arguments and data for and against eliminative materialism of pain. If eliminativism is correct, then the version of type identity theory of pain I propose in this project is strictly false. While pain folk psychology has stimulated much psychological research resulting in improved clinical outcomes for some pain patients, our own intellectual history reveals that any theory can seem successful even when it is radically false. Neuroscience already shows that many folk pain claims are false, while the truth of many others is not known. Eliminative materialism implies the disquieting consequence that the limit of what can be scientifically eliminated or reduced is much closer than we may conventionally think. Alternately, since intellectual history also offers modest evidence of theoretical co-existence between type identity theory of mind and folk psychology, radical theory change as advocated by eliminativism is just one end-point on a continuum of many possibilities. Still, accommodation such as this cannot change the sobering insight that all human knowledge is ultimately provisional. This realization encourages guarded humility about the ontological status of existing folk and scientific pain theories, including the type identity theory of pain, while it fosters an equally guarded optimism concerning our future theoretical prospects.